Device Tested That Zaps Asthmatic Airways

May 22, 2006
Device Tested That Zaps Asthmatic Airways
By THE ASSOCIATED PRESS

Filed at 10:08 p.m. ET

WASHINGTON (AP) -- In a radical experiment, doctors are snaking wires inside the lungs of asthma patients to essentially burn off some of the tissue that blocks their ability to breathe.

Called bronchial thermoplasty, the procedure is the first attempt at a non-drug treatment for asthma.

It's not without risk. Irritating those super-sensitive airways can trigger wheezing, and no one knows the long-term effects. Nor does it promise a cure.

But the hope is that physically altering spasm-prone airways might one day help thousands of patients with hard-to-control asthma breathe easier.

''People still get very sick from asthma. People still die of asthma. You'd think we'd have better control, but it seems to be escalating rather than going down,'' says Dr. Michael Simoff, interventional pulmonology chief at Detroit's Henry Ford Medical Center, one of 17 U.S. hospitals, and 29 worldwide, enrolling patients in the experiment.

''We have a real potential here, I think, to influence a very common disease.''

More than 20 million Americans have asthma, and the chronic lung disease is on the rise. While medications can be very effective in preventing and treating asthma attacks, the disease kills 5,000 people every year and accounts for 2 million emergency-room visits.

The thermoplasty experiment targets patients who do poorly despite multiple medications -- based on evidence that overgrown muscle tissue lining air tubes inside the lungs is one of asthma's underlying causes.

So-called smooth muscle encircles those airways. When something irritates the lungs, the muscle spasms, narrowing air passages to leave patients gasping. Swelling further closes off their air. Repeated attacks thicken muscle so airways can become habitually narrowed, and the muscle becomes even more sensitive to asthma triggers.

Bronchial thermoplasty promises to get rid of half of that thickened muscle, in hopes that the airways will behave more normally.

Doctors sedate patients and thread a bronchoscope -- a lighted catheter -- through the nose or throat and into the branch-like airways that fill the lungs. A wire basket on the tip is inflated to touch the airway walls, and radiofrequency waves are beamed through those wires.

Simoff compares it to a microwave oven, which cooks meat without scorching the outer skin like a grill would. The RF waves work similarly: They appear to beam through the airway's thin lining without scarring it, while heating smooth muscle underneath to 149 degrees -- hot enough that some muscle tissue basically disintegrates.

It takes three outpatient treatments, a half-hour each, to inch the RF device throughout the lungs, reaching main airways.

Coughing and wheezing are common side effects for a few days, but clear once lung irritation subsides, says Dr. Gerard Cox of Canada's McMaster University, who reported the first study results -- on 16 patients tracked for two years -- this month in the American Journal of Respiratory and Critical Care Medicine.

Most breathed a little bit easier on an asthma test and had more symptom-free days by three months after treatment, he reports. A second pilot study of 108 patients found similar improvements in the half given thermoplasty, researchers reported Monday at an American Thoracic Society meeting.

Now under way is the real test, a clinical trial funded by device manufacturer Asthmatx Inc. that is enrolling at least 300 severe asthmatics. Some will get thermoplasty and some a sham procedure -- the bronchoscope snaked into their lungs but not heated.

Physically manipulating already hypersensitive airways is uncharted territory. It's crucial to track recipients for at least five years to watch for late-term side effects, cautions Dr. Michael Silver of Chicago's Rush University Medical Center, who is monitoring the research and describes himself as ''just this side of skeptical'' that it will pan out.

Among concerns: Do the airways become too weak, or does late scarring arise? How long do any benefits last?

Silver also wonders about the price tag. Asthmatx won't yet estimate that, but simple bronchoscopies cost up to $2,000 each.

The procedure doesn't replace asthma medications, stresses Dr. Rand Sutherland of Denver's National Jewish Research and Medical Center. But he's testing it because too many patients run out of options: ''We long for something else.''

Indeed, ''I didn't really feel like I had a lot to lose,'' says Rod Bailey, 59, of Leicester, England. He wheezed and gasped daily despite six medications before undergoing thermoplasty two years ago.

The first procedure triggered a bad asthma attack -- but he says he hasn't had one since. Bailey calls his asthma so improved that he cut his steroid inhaler use by half and is about to go whitewater kayaking.